| ITF - W35 Klagenfurt | 06/02 09:00 | 29 | [341] Sofia Costoulas v Marie Benoit [286] | 1-6,3-6 | |
| ITF - W35 Klagenfurt | 06/01 14:00 | 28 | Sofia Costoulas v Cagla Buyukakcay | 2-6,6-1,6-4 | |
| ITF - W35 Klagenfurt | 05/30 07:50 | 27 | Wakana Sonobe v Sofia Costoulas | 4-6,6-7 | |
| ITF - W35 Klagenfurt | 05/29 09:10 | 26 | [212] Oana Gavrila v Sofia Costoulas [341] | 0-6,2-6 | |
| ITF - W35 Klagenfurt | 05/28 07:30 | 25 | [404] Elena Malygina v Sofia Costoulas [341] | 3-6,6-3,4-6 | |
| ITF - W35 Annenheim | 05/24 10:35 | 28 | [281] Sofia Costoulas v Tereza Valentova [334] | 5-7,1-6 | |
| ITF - W35 Annenheim | 05/23 16:00 | 27 | [281] Sofia Costoulas v Nika Radisic [378] | 6-2,6-3 | |
| ITF - W35 Annenheim | 05/22 15:30 | 26 | [281] Sofia Costoulas v Mara Guth [501] | 2-6,6-1,6-3 | |
| ITF - W35 Annenheim | 05/22 07:00 | 25 | Sofia Costoulas v Mila Masic | 6-2,6-2 | |
| ITF - W35 Bastad | 05/09 08:10 | 26 | [457] Irina Fetecau v Sofia Costoulas [291] | Retired | |
| ITF - W35 Bastad | 05/07 11:25 | 25 | Maileen Nuudi v Sofia Costoulas | 2-6,6-7 | |
| Billie Jean King Cup | 04/13 19:05 | 64 | Emma Navarro v Sofia Costoulas | Cancelled | |
| Billie Jean King Cup | 04/12 22:00 | 64 | [5] Jessica Pegula v Sofia Costoulas [279] | 4-6,6-2,6-3 | |
| ITF - W50 Kashiwa | 04/05 03:15 | 27 | [356] Ya-Hsuan Lee v Sofia Costoulas [285] | 6-1,6-2 | |
| ITF - W50 Kashiwa | 04/04 03:30 | 26 | [285] Sofia Costoulas v Priscilla Hon [189] | 6-2,6-2 | |
| ITF - W50 Kashiwa | 04/02 03:40 | 25 | [285] Sofia Costoulas v Sohyun Park [299] | 6-2,6-2 | |
| ITF W50 - Kofu | 03/28 03:10 | 26 | [286] Sofia Costoulas v Destanee Aiava [196] | 3-6,4-6 | |
| ITF W50 - Kofu | 03/27 04:00 | 25 | Sofia Costoulas v Rin Nakagawara | 6-1,6-2 | |
| ITF - W15 Hinode | 03/23 01:00 | 28 | Sofia Costoulas v Maegan Manasse | 2-6,3-6 | |
| ITF - W15 Hinode | 03/22 00:55 | 27 | Sofia Costoulas v Dabin Kim | 3-6,6-3,6-0 | |
| ITF - W15 Hinode | 03/21 04:20 | 26 | Sofia Costoulas v Kisa Yoshioka | 6-0,6-3 | |
| ITF - W15 Hinode | 03/20 05:00 | 25 | Sofia Costoulas v Yui Chikaraishi | 6-0,6-2 | |
| ITF - W35 Santo Domingo | 03/13 13:25 | 25 | [279] Sofia Costoulas v Maria F H Gonzalez [205] | 6-0,3-6,3-6 | |
| ITF - W35 Santo Domingo | 03/08 15:15 | 27 | [226] Elvina Kalieva v Sofia Costoulas [279] | 6-7,6-4,6-0 | |
| ITF - W35 Santo Domingo | 03/07 16:15 | 26 | [278] Varvara Lepchenko v Sofia Costoulas [279] | 6-7,4-6 | |
| ITF - W35 Santo Domingo | 03/06 15:05 | 25 | [471] Maria Sara Popa v Sofia Costoulas [279] | 2-6,5-7 | |
| ITF - W50 Pretoria | 02/27 10:05 | 25 | [296] Jaeda Daniel v Sofia Costoulas [274] | 7-5,6-2 | |
| ITF - W50 Pretoria | 02/20 13:00 | 25 | [377] Kaylah McPhee v Sofia Costoulas [274] | 6-3,6-2 | |
| ITF - W50 Roehampton | 02/15 13:35 | 26 | [278] Nikola Bartunkova v Sofia Costoulas [276] | 6-3,6-1 | |
| ITF - W50 Roehampton | 02/14 09:55 | 25 | [493] Johanne C Svendsen v Sofia Costoulas [276] | 4-6,3-6 |
Sofia Costoulas (born 2 April 2005) is a Belgian tennis player.
Costoulas has a Greek–Congolese father and a Belgian mother.
Costoulas has a career-high singles ranking by the Women's Tennis Association (WTA) of 248 and a best doubles ranking of 229.
On the ITF Junior Circuit, she had a career-high combined ranking of No. 2, achieved on 18 April 2022. She lost the girls' singles final of the 2022 Australian Open to Petra Marčinko. She had already reached the Wimbledon junior doubles final in 2021.